Update Travis Ubuntu version to Bionic

Author: 64kramsystem

.travis.yml

@@ -1,3 +1,4 @@
+dist: bionic
 language: ruby
 cache: bundler
 bundler_args: --without tools
@@ -7,10 +8,6 @@ rvm:
   - 2.3
   - 2.4
   - 2.5
-addons:
-  apt:
-    sources:
-      - mysql-5.7-trusty
-    packages:
-      - mysql-server
+services:
+  - mysql
 sudo: required